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oracle 数据库中查询重复数据:
select * from employee group by emp_name having count (*)>1;
oracle 查询可以删除的重复数据
select t1.* from employee t1 where (t1.emp_name) in (select t2.emp_name from employee t2 group by emp_name having count (*)>1) and t1.emp_id not in (select min(t3.emp_id) from employee t3 group by emp_name having count (*)>1);
oracle 删除重复数据
delete from employee t1 where (t1.emp_name) in (select t2.emp_name from employee t2 group by emp_name having count (*)>1) and t1.emp_id not in (select min(t3.emp_id) from employee t3 group by emp_name having count (*)>1);
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Oracle字符串函数length、upper、lower、initcap、 concat、instr、replace
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